Thyroid fine-needle aspiration (FNA) biopsy is generally considered a very safe procedure. However, like any medical procedure, it carries some minor potential risks. These risks typically include minor bleeding or bruising at the biopsy site, a slight chance of infection, and, very rarely, damage to structures near the thyroid gland. The risk of damaging nearby structures is extremely low due to the procedure being performed under ultrasound guidance. Additionally, there's a possibility that the FNA biopsy results may not definitively determine if a nodule is cancerous. Should this occur, a repeat biopsy might be necessary.